1. Field of the Invention
The present invention relates to a process for producing new conductive polymers, more particularly, carbon dichalcogenide polymers.
2. Description of the Prior Art
Conductive high molecular materials comprising a polymer skeleton having conjugated carbon-to-carbon double bonds have been synthesized heretofore. Examples of them include polyacetylene, polypyrrole, polyphenylene and polyphenylenevinylene. Further, polymers having chalcogenide atoms in the skeleton and apparently no conjugated double bonds but having semiconductivity or conductivity as proved by doping have been known. They include, for example, polyphenylene sulfide, polyphenylene selenide, polyphenylene telluride and polyvinylene sulfide. Among them, polymers prepared from carbon disulfide, carbon diselenide or carbon ditelluride may be assumed to have possible use as the conductive high molecular materials, though they do not have conjugated double bonds.
Only few investigations were made on the polymerization of carbon disulfide and its polymer was synthesized by only Bridgman [Proc. Am. Acad. Arts. Sci., 74, 399 (1941)]. According to his process, carbon disulfide is polymerized at 185.degree. C. under about 55 kbar in a pressure vessel for several hours to form a black, powdery polymer. However, the polymer cannot be prepared easily, since very severe conditions are required, namely, carbon disulfide having a boiling point of 46.degree. C. must be kept at a high temperature under a pressure of as high as above 50 kbar. In addition, the polymer thus obtained is an insulater having a conductivity of as low as below 10.sup.-14 S/cm. Even when the polymer is doped, its conductivity is improved only slightly. For example, when it is doped with 5 molar % of iodine, the conductivity is increased to, at the highest, only 10.sup.-10 S/cm.
On the other hand, it has been known that carbon diselenide can be polymerized at a temperature of 100.degree. to 200.degree. C. under about 5,000 atm [Y. Okamoto and P.S. Wojciechowski, J. Chem. Soc., Chem. Commun. 386 (1982) and H. Kobayashi et al., Chem. Lett., 1407 (1983)].
However, this process cannot be considered to be an easy process for producing the polymers, since the pressure of as high as 5000 atm is required for the synthesis and the physical properties of the obtained polymers are poor.